I didn't know, so I Googled up how starters work. It said that the old Bendix drive had the gear on a helical cut shaft. After the car engine started it would drive the starter gear down the helix and out of engagement with the flywheel. But, it said the Bendix drive is obsolete and more modern starters have a one way "sprag" drive that is like a one way clutch. So, the starter gear does not slide laterally on the starter shaft, which is good for our use. Good luck with your build.